# Walter Roberson

I do not do free private consulting. If you want to bring my attention to something, send a link to the MATLAB Answers location. I am currently caught up to T0099119; if you are waiting on a reply from me for an older issue, please send me a reminder.

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**Content Feed**

Calculate the area of geometry

The first thing you need to do is decide how the user is going to represent the specific shape for calculation purposes. are y...

2 hours ago | 0

How to distribute random points outwards from a center location?

cx = 3; cy = 5; %as appropriate R = 20; N = 1000; theta = rand(1, N) * (2 * pi); rbase = rand(1,N) * R; [X, Y] = pol2cart...

2 hours ago | 0

Problem using variable='z^-1' in Z transform with Z^-1 format

Setting the Variable property afterwards just changes the Variable property, without reinterpretting the matrices. It is not a c...

3 hours ago | 0

MAJOR 25+ YEAR OLD MATLAB BUG. PLEASE, PLEASE FIX! Ctrl-C doesn't work, no way to stop a process.

| appreciate that there are issues with OS implementations, eg memory management, that make this a challenge. That said, I'm qu...

3 hours ago | 0

got new laptop; can't access matlab from it

https://www.mathworks.com/downloads/ for downloads. You will probably need to deactivate against the old system to activate on ...

9 hours ago | 0

Has anyone got aaS Matlab toolbox I need it soon kindly help I will be very grateful to you

The current student software downloads are linked from https://www.ansys.com/academic/students Ansys aaS appears, however, to ...

9 hours ago | 0

find 1s in the Matrix

firstcol = 48; lastcol = 65; offsetcol = 14; idx = firstcol:lastcol; offsetidx = idx-offsetcol; result = YourMatrix(:,offse...

9 hours ago | 0

| accepted

Drawing a boundary box around an image?

My goal is to create a bounding box around the non-zero pixel value region of my image. filename = 'https://www.mathworks.com...

10 hours ago | 0

| accepted

Poisson distribution and discrete distribution

fitdist allows you to fit a distribution to data. I want to fit Y to a Discrete distribution There are an infinite number of d...

10 hours ago | 0

creating a function nonpivotcols that takes a m*n matrix as input and produces a matrix consisting of the nonpivot columns of the input

[R pcols]=rref(A); A(:,pcols)=[]; You deleted the pivot columns out of A. Whatever is left must be non-pivot columns. [r,fcol...

10 hours ago | 0

Why does sqlread() not work?

sqllite() is not a Mathworks function. sqlread() is a method that applies to some objects created by the database() command. h...

11 hours ago | 0

What does it mean to "% extract t and h(t) for time range 5.0<=t<=12.0" when "h=4.0+6.0*t*10^-0.5-(4*10^-0.25)*cos(0.75*pi*t)"?; when

One way: Loop over the indices of the vector of t. At each point, make the "current" t equal to the t vector indexed at the cur...

12 hours ago | 0

Select multiple radiobutton at the same time

hf=exemple; You run the code in exemple and it returns. You are no longer running any code inside exemple but it set up sev...

21 hours ago | 0

Cannot execute Figure(3).

q=[0.000000025;0.000000034;0.000000042]; %Calculate manually on 0.75Q, Q, 1.25Q; f=1-exp(-(((k*pi*d)/q))*z); The / opera...

21 hours ago | 0

Unrecognized function or variable 'Fid2'.

l = fgetl(FID); if strcmp(l(1),'**') fgetl returns a character vector (except at end of file) l(1) will be a sing...

24 hours ago | 1

| accepted

Simulink files compatibility with MATLAB versions

Yes. The Function Block (not the same as MATLAB Function Block) no longer exists. You might want to hold on to one of your previ...

1 day ago | 0

GPU coder :basic Code Generation failed

I think Cuda Toolkit 11.6 is not supported in your release. I am having difficulty finding the toolkit version that is supported...

1 day ago | 0

which part of my logic is wrong?

You used the / operator. The / operator is matrix division. P/Q is approximately P*pinv(Q) . In situations such as yours with ro...

1 day ago | 1

| accepted

trisurf: Removing Unwanted Lines and Surfaces from Irregular 3D Plot

You should not do this at the trisurf() level; you should be creating a modifed triangulation https://www.mathworks.com/help/ma...

1 day ago | 0

3D plot in Simulink

XY Graphs are specifically documented to open a different window for each block, and only permit scalar X and scalar Y. But you ...

1 day ago | 0

Calculating Hessian without using symbolic functions

No, not unless you can calculate it by hand ahead of time using some other set of external tools. You can estimate the Hessian....

1 day ago | 0

out of memory error

Pre-allocate out to the final size. This will reduce temporary memory use. Also, using : is more memory efficient than indexing ...

1 day ago | 0

How do I prevent MATLAB from converting characters into their ASCII equivalent?

zeros() creates a numeric array, with a default data type of double() Any time you assign a char() into a numeric array, MATLAB...

1 day ago | 0

Incorrectly getting a blank video when using videowriter function to display data

You are not changing the display between getframe() so all of the frames would be the same. If you have pre-computed frames sto...

1 day ago | 0

Linear constraints using lsqnonlin

lsqnonlin() does not support constraints other than upper bound and lower bound. I suggest you minimize the norm() of F(x,y,z)-...

1 day ago | 0

i couldn't understand the problem in it

dy = zeros(12,1); You initialize 12 return values but you then only store up to dy(9). You only need zeros(9,1)

2 days ago | 0

| accepted

minibatchqueue or arrayDatastore drops my data precision from double to single

Gpu training does not support double precision. If you look at the available options, precision cannot be selected.

2 days ago | 0

How do I plot a summation equation?

You are summing exp() of values that are purely imaginary and are mostly not integer multiples of π. The individual entries are ...

2 days ago | 0

How to change the matlab maximum name length?

No there is no way to do that. The variable names and field names of struct and property names of objects are all stored as fixe...

2 days ago | 0

dividing defined variable by named variable

a=sqrt((d.^2)*(3^2)) 3^2 is 9 so inside the sqrt() you have 9*d^2. sqrt() of that is sqrt(9)*sqrt(d^2). For positive d that...

2 days ago | 0